Particle accelerators find many applications in fundamental research, as well as in health, energy and security applications. They range from relatively compact, sometimes even table top devices to km-size particle colliders to unravel the secrets of the universe. In order to reduce the size, costs and complexity of these facilities, particle-driven plasma wakefield acceleration is a very promising alternative to commonly used radiofrequency accelerators. High quality electron beams can act as ideal driver for a plasma that is then used to produce a very high accelerating gradient of the order of GV/m – that is a potential difference of 1 Billion Volt over one meter – to accelerate another electron beam to high energy. The high repetition rate of such scheme is another advantage that shows high promise for a number of application.